Antiskid brake control apparatus for sensing changes in the absolute rotational speed of a vehicle wheel

ABSTRACT

An antiskid brake control system having means for sensing changes in the absolute rotational speed of a vehicle wheel. The sensing means includes a hermetically sealed housing, an inertial mass arranged within the housing and rotatable relative to the housing within a limited angular range, an electrical signaling device responsive to the relative rotation between the inertial mass and the housing and at least one electrical conductor connected to the signaling device and passing through the housing. The brake control system is also provided with an electrically actuatable device for controlling the brake pressure applied to the sensed wheel and an electrical line interconnecting the sensing means with this control device. According to the invention, the sensor housing and the vehicle wheel or a member rigidly connected with the vehicle wheel are provided with means for detachably coupling these two parts together. Contact elements are also provided, beneath the side of the sensor housing that faces the wheel, to detachably connect the electrical line to the electrical conductor.

United StatesPatent [72] Inventors Heinz Leiber 3,503,653 3/1970 Daviset al. l88/l8lX Enklen; Primar E G y xammereorge E. A. Halvosa Heinzwehde He'delberg Germany Assistant Examiner-John J. McLaughlin, Jr. {2%2:13 1969 Attorney-Spencer & Kaye a [45] Patented Feb. 16, 1971 [73]Assignee Teldix GmbH 32 P g g i g ABSTRACT: An antiskid brake controlsystem having means nomy for sensing changes in the absolute rotationalspeed of a vehii??? 6 cle wheel. The sensing means includes ahermetically sealed I housing, an inertial mass arranged within thehousing and rotatable relative to the housing within a limited angular[54] ANT-SKID BRAKE CONTROL APPARATUS FOR range, an electrical signalingdevice responsive to the relative SENSING CHANGES IN THE ABSOLUTErotation between the inertial mass and the housing and at leastROTATIONAL SPEED OF AVEHICLE WHEEL one electrical conductor connected tothe signaling device and passing through the housing. The brake controlsystem is 21 CIIIIIISS Drawing Figs. i

also provided with an electrically actuatable device for con- [52] US.Cl. 188/181; trolling the brake pressure applied to the sensed wheel andan 303/21 electrical line interconnecting the sensing means with this[51] Int. Cl. B60t 8/16 comm] devicev According to the invention, theSensor housing [50] Fleld Search 73/(Inqutred); and the vehicle wheel ora member rigidly connected with the 188/181; 303/6, 6l 63 vehicle wheelare provided with :means for detachably coupling these two partstogether. Contact elements are also [56] References cued provided,beneath the side of the sensor housing that faces the UNITED STATESPATENTS wheel, to detachably connect the electrical line to the electri-3,477,765 11/1969 Perrino l88/l8lX cal conductor.

as 32 3s 7 T 33 I y I VVVV H I ,--'17 PATENTED FEB 1 1am sum 1 or 3mvslvroks Heinz Lelber8 Heinz Wehde 9%wm 7% 15 FIG. 2

FIG.|

ATTORNEYS FIG. 3

INVEN TORS Hein-i Leiber 8| Heinz Wehdq ATTORNEYS PATENTEDFEBWQYII3,563,351

I SHEET30F3 IN VEN TORS Heinz Leiber8 Heinz Wehde arromvevs ANTISKIDBRAKE CONTROL APPARATUS FOR SENSING CHANGES IN THE ABSOLUTE ROTATIONALSPEED OF A VEHICLE WHEEL BACKGROUND OF THE INVENTION The presentinvention relates to an antiskid brake control system suitable for usewith wheeled vehicles. The system is of the type having a sensor formonitoring changes in the absolute rotational speed of a vehicle wheel.The sensor comprises a hermetically sealed housing, an inertial massarranged within the housing and rotatable relative to the housing withina limited angular range, an electrical signaling devicee.g. mechanicallyactuated electrical contacts-responsive to the relative rotation betweentheinertial mass and the housing and at least on one electricalconductor connected to the signaling device and passing through thehousing.

The antiskid brake control system is also provided with an electricallyactuatable device for controlling the brake pressure applied to thesensed wheel. This control device is connected to the electricalconductor or conductors of the sensor described above by means of asuitable electric line. The brake pressure control device is operable,under control of the electrical signaling device of the sensor, toreduce the brake pressure applied to the vehicle wheel if the wheel hasa tendency to lock or skid.

The term absolute rotational speed of the wheel," as used in thisapplication, is intended to refer to the rotational speed of a vehiclewheel relative to the earth. This absolute speed is to be distinguishedfrom the rotational speed of the wheel when viewed, for example, from apoint on the vehicle chassis. This distinction is best explained by aconsideration of the construction of antiskid brake control system wheelsensors of the prior art.

Antiskid brake control system wheel sensors, of the type which measurechanges in the rotational speed of a wheel by means of an inertial massand a signaling device, are conventionally driven via gears, frictionwheels or some other suitable drive member which senses the rotations ofthe vehicle wheel. The drive member is connected to a drive spindle ofthe sensor which protrudes from the sensor housing; this sensor housingis rigidly fastened to the vehicle chassis.

Since the drive member of the wheel sensor would be caused to turn ifthe chassis of the vehicle were made to rotate with respect to thewheel, even if the latter were held stationary, it may be seen that therotational speed of the vehicle wheel is viewed relative to the vehiclechassis. Although this relative speed may, in some cases, be a closeapproximation of the absolute rotational speed of the vehicle wheel, thedifferences are large enough to cause an increase in the stoppingdistance of the vehicle when the sensor is used in a highly sensitiveantiskid brake control system.

To illustrate the effect of measuring changes in the rotational speed ofthe wheel with respect to the chassis, let it be assumed that the sensorhousing is fastened to the brake backing plate and that a driving memberdisposed on the sensor drive spindle is in engagement with a gear ringfastened to the wheel. Due to the torque applied by the brakes to thewheel suspension system, the brake backing plate will be rotated in thedirection of the wheel during the braking process by a not insignificantangle and, upon sudden release of the brake, in the opposite direction.The rotational deceleration of the wheel, as measured by the sensorduring the braking process, will thus be less than the actualdeceleration and, when the brake is released, the sensor willmisleadingly indicate a rotational acceleration which does not occur atthe wheel, at least not in the measured intensity.

In certain limited cases in the prior art, it has been possible toconstruct wheel sensors which measure changes in the absolute value ofthe rotational speed of a wheel. These sensors are no different in theirbasic construction from the relative value sensors described above. Withthese sensors, however, there is a direct (as opposed to gear or otherintermediate) connection between the drive spindle of the sensor and thewheel. This direct coupling has only been possible in the cases where afree end of an axle shaft rotating with the wheel is arranged toprotrude from a part that is rigidly connected to the vehicle. In thisevent, the sensor housing can be fastened to the pan connected to thevehicle and the end of the axle shaft connected to the drive spindle ofthe sensor.

An example of such an absolute value sensor may be found in certainprior art wheel sensors employed for railroad vehicles. Since the wheelbearings for track-following axles are normally disposed on the outsideof the vehicle, with the wheels on the inside, a free end of each axleshaft protrudes from a bearing sleeve. The drive spindle of the wheelsensor can therefore be directly coupled to this axle end while thesensor housing can be attached to the bearing sleeve orsome othernonrotating member of the wheel suspension system.

In the case of driven vehicle wheels which have a bearing located at apoint inside of the wheel, nondriven wheels having a hub which rotatesabout a stationary axle, as well as with dual wheels which are mountedclosely together on both sides of a common bearing, it is not possibleto provide a direct coupling to wheel sensors of conventional design topermit measurement of changes in the absolute rotational wheel speed.Since most of the present motor vehicles and aircraft are provided withwheel suspension systems and landing gear, respectively, which fallwithin one of these three categories, it has not normally been possibleto sense-the absolute rotational speed, or variations thereof, of thevehicle wheels.

The difference between a measurement of the relative rotational speedand the absolute rotational speed of a wheel has, until now, not beenappreciated in connection with antiskid control systems for vehiclebrakes. The present invention is therefore based on this new realizationthat an antiskid brake control system can only effect the optimumvehicle deceleration when the absolute value of the vehicle wheel speedis monitored. The present invention provides a means for measuring thechanges in the absolute speed of a vehicle wheel even with wheelsuspension systems which, thus far, have not been adaptable for the useof such a sensor.

The sensors of the prior art which comprise an inertial mass and anelectrical signaling device have also always required at least oneslipring or an equivalent arrangement for transmission of the electricalsignals between the rotating and the nonrotating parts. Such a signaltransmission arrangement has the disadvantage of increasing the size andcomplicating the structure of 'the sensor particularly when thesignaling device-e. g.

the electrical contacts fastened to, and rotating with, the drivespindle together with the inertial mass, which is rotatable relative tothe drive spindle within a limited angular range, are hermeticallysealed in a special housing to protect them against corrosion and dirt.This special housing, which also rotates, must consequently be disposedin a second stationary outer housing with thesignal transmission devicearranged in the space between the two housings.-

SUMMARY OF THE INVENTION An object of the present invention, therefore,is to provide a wheel sensor for an antiskid brake control system formeasuring changes in the absolute rotational speed of a vehicle wheel.

It is a further object of the present invention to provide a wheelsensor, of the above-defined type, which may be installed in vehicleshaving any conventional type of wheel suspension.

It is still a further object of the present: invention to provide awheel sensor, of the above-defined type, which is smaller in size andless complicated in structure than the wheel sensors of the prior art.

These objects, as well as other objects which will become apparent inthe discussion that follows, are achieved, according to the presentinvention, by providing a sensor which consistsonly of a hermeticallysealed housing, an inertial mass arranged within the housing androtatable relative to the housing within a limited angular range, anelectrical signaling device responsive to the relative rotation betweenthe inertial mass and the housing and at least one electrical conductorconnected to the signaling device and passing through the housmg.

This sensor is constructed so as to be attachable either directly to thevehicle wheel or to a member rigidly connected with the vehicle wheel.Contact elements are also provided, beneath the side of the sensorhousing that faces the wheel, to detachably connect the electricalconductor or conductors to the electrical line that leads to the brakepressure control device.

Since this sensor, according to the present invention, requires noconnection to a vehicle chassis, it can be installed on any'type ofwheel that is mounted on motor vehicles or aircraft. It is immaterial,in this case, whether the wheels are driven or not or whether they aremounted on a particular type of bearing or suspension system. The sensorcan be mounted at any desired point on the vehicle wheel, as long as therotational axes of the wheel and of the rotating inertial mass areparallel. This sensor is substantially simpler in construction than thesensors used in the prior art and, due to the encapsulating housing, itis very resistant to the rough conditions of vehicle operation.

Although it is still necessary to provide a signal transmission device,such as sliprings and brushes, to pass the electrical signal or signalsfrom the signaling device within the rotating sensor to the brakepressure control device within the vehicle chassis, such a signaltransmission device can now be constructively separated from the sensorhousing. As a result, the signal transmission device can be adapted tothe particular type of wheel suspension so that it can be bestaccommodated in the available space and be made as reliable as possible.

The installation and removal of the sensor according to the presentinvention may be accomplished particularly quickly and simply. The meansfor connecting the sensor to the vehicle wheel or the member rigidlyconnected with the vehicle wheel as well as the electric contacts whichare provided beneath the floor of the sensor housing for detachablyconnecting the signaling device within the sensor to the brake controldevice in the vehicle chassis make it possible to easily attach anddetach the sensor.

The requirement that the sensor be mounted on the wheel itself or on amember rigidly attached to the vehicle wheel is not the sole reason whythe sensor according to the present invention may be used with all typesof wheel suspension systems. lt is also important, as required by thepresent invention, that the electrical connections between the sensorand the brake control device be effected in the mounting plane. Thispermits the problem of locating and constructing the signal transmissiondevice to be separated from the problem of constructing and mounting theactual sensor. The signal transmission device can then be adapted to theparticular type of wheel suspension that is used. This separation hasthe additional advantage that it permits the use ofa single type ofsensor for all the wheels of a single vehicle and even for vehicles ofdifferent kind and type.

When the contacts are constructed, according to a further development ofthe present invention, so that they automatically effect the electricalconnection upon installation of the sensor and interrupt the connectionwhen the sensor is removed, the installation and removal of the sensoris additionally simplified.

The present invention is entirely unrestrictive as to the location atwhich the sensor is mounted to the wheel. The sensor may, for example,be arranged eccentrically with respect to the axis of the wheel; in mostcases, however, two modifications of a central arrangement-both being atthe outside of the wheel due to its easy accessibility-will bepreferred. If the wheel has a nonrotating axle and a rotating hub, it isespecially practical to fasten the sensor to the hub as an axialextension thereof, and to construct the contacts as axial slip contactswhich are disposed, on the one hand, on the frontal side of thenonrotating axle and, on the other, at the bottom of the sensor housing.These contacts thus serve as a very simple type of signal transmissiondevice, a device which can be made particularly wear resistant andreliable in operation if the contacts are arranged as a point contact atthe axis of rotation.

If the wheel is driven or if a short axle shaft is connected to thewheel to support the wheel, the sensor may be mounted as an axialextension of this wheel-connected axle with the contacts formingstationary contacts. The signal transmission device must then bedisposed at another location in the vicinity of the wheel bearings.

ln both cases described above it is advisable to provide a cavity at thefrontal end of the axle to hold the contacts. From this cavity theelectric line, connected to one of the contacts, is passed through alongitudinal bore in the axle either to the signal transmission deviceor die directly to the brake control device. If the wheel is mounted onthe short axle, the axle can be provided with a bore extending itsentire length or it can have a longitudinal bore which bends in thedirection of the axle circumference, passing through none or only one ofthe wheel bearings. In the extreme case only a short oblique bore isrequired.

The arrangement of the signal transmission device, which preferablyconsists of sliprings and brushes, may be of any suitable design toprotect it against damage by gravel and dirt it may be preferable toarrange it next to the wheel bearing, within the housing which must beprovided to hold the bearing lubricant. Grease will not impair thecontact between sliprings and brushes so long as suitable materials areused.

In order to reduce the number of electric lines between the sensor andthe brakecontrol device, it is further proposed to utilize the groundconnection between wheel and chassis. in the case of ball or rollerbearings the two bearing races are electrically connected via the ballsor rollers. The groundconnection between brakeshoes and brake drum orbrake disc is parallel to this conductor path; however, the brake liningnormally exhibits a high resistance. According to a particularembodiment of the present invention, it is proposed that this resistancebe reduced by embedding an insert, consisting, for example, of brass inthe friction linings. The insert should be designed to wear at the samerate as the linings. If this measure is not effective to sufficientlyreduce the ground resistance, an additional slip brush may be providedin the bearing. Such a brush is still substantially less expensive thana second slipring arrangement, which must be insulated with respect toground.

It is also possible to replace the slipring brush arrangement with aninductive signal transmission device that may consist, for example, oftwo coaxial electromagnetically coupled annular coils, one of which ismounted on the wheel, the other on the axle.

In many cases, particularly with motor vehicles, it is preferable toprovide for removal of sensor and wheel independently of each other. Forthis reason a central arrangement of the sensor may be more favorable;because it is then possible, by making the external diameter of thesensor housing smaller than the inner diameter of the center opening inthe rim, to remove the rim without removing the sensor.

Finally it should be mentioned that the present invention is not limitedto sensors which monitor rotational deceleration and acceleration.Instead of a balanced rotational mass it is also possible, for example,to provide an inertial mass mounted eccentrically to its center ofgravity and outside of the theoretical wheel axis so that its deflectionwith respect to an elastic resetting force will be a measure of therotational speed itself. Such a deflection could then be electricallytransmitted to a brake control device which further processes thismeasured value.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is cross-sectional view of anondriven wheel and a wheel sensor mounted centrally thereon, inaccordance with a first preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1.

FIG. 3 is a cross-sectional view of an axle-driven wheel and a wheelsensor mounted centrally thereon, in accordance with a second preferredembodiment of the present invention.

FIG. 4 is a cross-sectional view of an axle-driven wheel and a wheelsensor mounted eccentrically on a counterbalanced sheet metal discattached to the wheel, in accordance with a third preferred embodimentof the present invention.

FIG. 5 is a cross-sectional view of modification of the signaltransmission device in the embodimentof the present invention shown inFIG. 4. l

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a nonrotatingwheel axle or a wheel pin 1 supporting a wheel hub 2. An only partiallyshown wheel rim 4 is fastened by means of bolts 3 to the hub 2 andprovided with a hubcap 6. The leftmost edge of the rim is indicated by adotted-dashed line 5. The wheel hub 2 runs on the tapered rollerbearings 7 and 8. The inner race of the bearing 8 is held by the widehead of an adjustment screw 9 which is screwed into a threaded hole inthe end of the axle.

A sensor housing 10 is screwed directly into a threaded bore 11 in thewheel hub 2. It is hermetically sealed by a cover 12 which rests on asealing ring 13 and is secured by a countersunk screw 14. In the housingthere is contained an inertial mass 15 as well as a signaling device inthe form of a contact arrangement 19 and 20. These contacts are bestviewed in the cross-sectional illustration of FIG. 2 taken along a lineim mediately to the right of the inertial mass. The inertial mass isrotatably mounted on two bearings 16 about a bearing pin 17 that ispressed into a hole at the bottom of the housing. An actuating pin 18,disposed in the inertial mass cooperates with the two flat contactsprings 19 and 20 and a further pin 21, also disposed therein,determines the rest position of the inertial mass. Both of these pinsappear in section in FIG. 2.

At the bottom of the sensor housing 10 is fastened an annular insulatingbody 22. Two small, rectangular blocks 23 and 24 are attached to thebody 22; the block 23 serves to hold the flat contacting springs 19 and20 while the block 24 holds two flat springs 25 and 26. The flat springs25 and 26 enclose, and apply pressure against the pin 21 of the inertialmass as well as a pin 27 that is inserted into the insulating body 22.The inertial mass can thus move from its indicated rest position withina limited angular region by bending the springs 25 or 26 in onedirection or the other. With a particularly heavy deceleration of thewheel the inertial mass will move in the direction shown by the arrow 28(FIG. 2). The pin 18 will then press against the contact spring 20 andbend it toward the left so that it will come in contact with the contactspring 19. This joinder of the springs 19 and 20 closes an electriccircuit and signals a reduction in the brake pressure applied to thewheel by a fluid-actuated brake (not shown). As a result, the wheel isallowed to accelerate again and skidding is prevented.

It should be mentioned, in this connection, that the illustrated innerconfiguration of the sensor is to be considered as only exemplary of themany signaling devices which may be used. Antiskid brake control systemshave been proposed, for example, which employ not only two but aplurality of contact springs so that two or more deceleration-dependentsignals will be produced depending on the value of the instantaneousrotational deceleration. Moreover, additional contacts can be providedto the right of the pin 18 to provide a signal indicative ofacceleration when the inertial mass rotates in the opposite direction.

Beneath the floor of the sensor housing-i.e. at the side thereof facingthe vehicle wheel--are arranged an electrical contact plate 30 and acontact pin 32. These contact elements function to transmit the signalproduced at the sensor signaling device within the rotating sensorhousing to a nonrotating electrical line which, in turn, is connected tothe electrically actuatable brake pressure control device. As may beseen in FIG. 1, the contact spring 20 is connected through theinsulating body 22 with the contact plate 30. This plate, which is alsoshown in broken lines in FIG. 2, is mounted on the outside of the floorof the sensor housing 10 on an insulating disc 31. The plate forms apoint contact with the axially movable contact pin 32, and the latter isconnected to the insulated electrical line 33 in a manner to bedescribed in detail below. This line is permanently connected to theabove-mentioned brake pres-- sure control device which is mounted in aconvenient place on the vehicle. The other contact spring 19 isconductively connected with the sensor housing 10, as shownschematically in FIG. 2. The housing 10 is in contact with the hub 2through the threaded coupling 11 and the hub is in contact with the axleand the metal portions of thevehicle chassis through the rollers of thebearings 7 and 8. The use of a "ground connection", in this manner,eliminates the need for an additional insulated transmission line.

The contact pin 32 is arranged to be axially movable within an insulatedbushing 34 and is maintained under pressure by a coil spring 35. Thespring is supported at its right-hand end by an insert 36 that ispressed into the insulating bushing. This insert, in turn, has aprojection toward the right which forms a plug pin 36a. A cableconductor 37 is soldered to the contact pin 32 and the insert 36 toensure a positive conductive connection between them. The insulatingbushing 34 is firmly pressed into the adjustment screw 9. The plug pin36a is inserted into a female receptacle 38 which is firmly held inplace in the interior of the axle by means of a further insulatinginsert 39. The stem of the female element is connected to theabove-mentioned line 33 which is passed through a longitudinal boreextending first centrally and then obliquely to the outside of the axle.

The antiskid brakecontrol system sensor can therefore be removed withoutdifficulty; as the sensor housing is unscrewed, the contact pin 32 willmove toward the left until its collar abuts against the insulatingbushing. Moreover, when the adjustment screw 9 is loosened-e.g. toexchange the bearings-the plug pin 36a will be simply withdrawn from thefemale element 38. Since the external diameter of the sensor housing isless than the inner diameter of the central opening in the rim of thewheel, it is also possible to dismount the rim without having to removethe sensor.

FIG. 3 shows a second embodiment of the present invention associatedwith a driven vehicle wheel which is connected to a so-called knockoutaxle 45.

This driven axle widens toward the left into a flange. The rim 4 as wellas a hat-shaped brake disc 47, which is not shown in FIG. 1, are screwedto this flange by means of extended wheel bolts 46. The knockout axle isbearing-mounted in a stationary axle tube housing 48 which supports thevehicle chassis, only the outer bearing, i.e. a ball bearing 49, beingshown.

The brake anchor contains two wheel brake cylinders; these wheelcylinders have pistons that press the brake linings 51 and 52 againstopposite sides of the outer, annular portion of the brake disc 47.

A profiled ring 54 is mounted on the frontal face of the axle tube 48 bymeans of screws 53. Its outer edge is constructed in the form of asealing ledge 54a which slides on a sealing ring 55 of syntheticmaterial inserted into the brake disc, thus forming a sealed annularchamber in the interior of the brake disc. This chamber can, forexample, contain the shoes of a drum-type parking or emergency brake(not shown).

The wheel configuration of FIG. 3 can employ the same wheel sensor as isshown in FIG. 1. In this case, however, the housing 10 is screwed to theknockout axle 45. The electrical line leading to the brake pressurecontrol device is connected to the plate 30 with the aid of the contactpin 32 which, unlike the case of FIG. 1, does not rotate with respect tothe plate. The contact pin is enclosed by the same insulating bushing 34as in FIG. 1. This bushing is pressed directly into the knockout axle.Instead of using the insert 36 with the plug pin 36a, a simple insert 56is provided here and directly soldered to the continuing line 57. Theline 57 is insulated and leads outwardly through an oblique bore to asignal transmission device which, in this example, consists of a carbonbrush 60 and a slipn'ng 58. The slipring surrounds the knockout axle ona ring of insulating material 59. The carbon brush is subjected to adownward pressure by a spring 61 and is connected to a furtherelectrical line 62 that leads to the brake pressure control device.

The carbon brush is located in a housing 63 of insulating material thatis mounted on the profiled ring 54. This housing is sealed by a cover 64of insulating material which extends into the insulating sheath of theline 62. The line 62 leaves the sealed annular chamber through anOpening 54b in the profiled ring and then passes along the chassis tothe brake pressure control device. The latter device evaluates thesignals originating from the sensor and controls pressure applied by theshoes 51 and 52.

The second galvanic conductive path between the wheel sensor and thebrake pressure control device is the ground connection between wheel andchassis. This ground connection is established-at least during thebraking actionnot only through the ball bearings 49 but also through thebrake. In order to provide this parallel path via the brake with aminimum passive ohmic resistance, the brake linings Sll and 52 areconstructed with a stud-type brass insert 65 that may also be connected,for example, to the body of the brake anchor 50 by means ofa flexibleelectrical cable 66.

FIG. 4 shows how a very similar sensor 70 may be eccentrically arrangedon a driven wheel. The illustration shows the entire wheel rim 4 and ahubcap 71. The axle is again marked 45 and the stationary axle tubehousing designated with the reference numeral 48. In addition to theslipring 58 and the brush housing 63 connected to the line 62, thisillustration shows a mount 72, welded to the axle tube housing 48 forholding the brake anchor 50.

Unlike the embodiment shown in FIG. 3, this embodiment of the presentinvention includes a sheet metal disc 73 disposed under the rim and heldby the wheel rim bolts. The floor of the sensor housing 70 is attachedto this disc with screws 74. A socket 75 of insulating material whichpasses through the sheet metal disc 73, the brake disc top and theflange of the axle is screwed together with the flange; this socketcontains a conventional plug arrangement that forms the electricalcontacts. The male contact element is fastened to the sensor andconnected with one of the two contact springs 19 or 20 shown in FIG. 2,whereas the female contact element is fastened in the socket 75 andconnected to an insulated line 76. The line 76 extends radially inwardat the axle flange and is permanently connected to the slipring 58.

The slightly modified sensor housing 70 extends through a suitableopening in the wheel rim 4. In order to maintain the balance of thewheel with this eccentric sensor arrangement, counterweight 77, suitablyadapted to the shape of the rim, is riveted to the opposite side of thesheet metal disc 73.

FIG. 5 shows an alternative embodiment of the signal transmission devicewhich may be used in the arrangement of FIG. 5. In place of the slipringand brush, there is shown a first induction coil 80 connected betweenthe line 76 leading to the signaling device ofthe wheel sensor andground, and a second induction coil 81 connected between the line 62that leads to the brake pressure control device and ground. These coilsare coaxially arranged about the axle 45 so that the inductance of thecircuit formed by the second coil and the line 62 will be influenced bythe position of the contacts 19 and 20 of the sensor '70.

When an alternating voltage is applied to the circuit formed by the line62 and the second coil 81, the inductance of this circuit will begreater when the contacts 19 and 20 are closed, than when they are open.If this inductance is continuously monitored, therefore, it may be usedas a signal" to operate the brake pressure control device.

it will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations.

We claim:

1. An antiskid brake control system for wheeled vehicles comprisingelectrically actuatable means for controlling the brake pressure appliedto a wheel; means for sensing changes in the absolute rotational speedof such wheel, said sensing means comprising a hermetically sealedhousing, an inertial mass arranged within said housing and rotatablerelative to said housing within a limited angular range, electricalsignaling means responsive to the relative rotation between said massand said housing and at least one insulated electrical conductorconnected to said signaling means and passing through said housing; anelectrical line connecting said sensing means with said brake pressurecontrol means; connecting means, associated with said housing and suchwheel, for detachably connecting said housing to such wheel; andelectrical contact means, arranged on one side of said housing, fordetachably connecting said electrical line with said electricalconductor.

2. The improvement defined in claim 1, wherein said connecting means isarranged to directly connect said housing to said wheel.

3. The improvement defined in claim 1, wherein said connecting meansincludes a member which is rigidly connected to said wheel and saidconnecting means is arranged to directly connect said housing to saidmember.

4. The improvement defined in claim I, wherein said contact means arearranged on the side of said housing which faces said wheel.

5. The improvement defined in claim 1, wherein said contact means areconstructed to provide an automatic connection between said electricalline and said electrical conductor when said sensing means is attachedto said wheel and to automatically disconnect said electrical line fromsaid electrical conductor when said sensing means is removed from saidwheel.

6. The improvement defined in claim 1, further comprising means fortransmitting a signal, during the rotation of said wheel, from saidelectrical signaling means in said sensing means to said means forcontrolling the brake pressure, said signal transmitting means beingseparately arranged from said sensing means.

7. The improvement defined in claim 6, wherein said wheel is mounted onat least one wheel bearing and said signal transmitting means isarranged in the proximity of said at least one wheel bearing.

8. The improvement defined in claim 1, wherein said sensing means isarranged on a common axis with said wheel.

9. The improvement defined in claim I, wherein said sensing means isarranged eccentrically with respect to the axis of said wheel.

10, The improvement defined in claim 8, wherein said wheel is arrangedto rotate about a nonrotatable axle, and wherein said electrical contactmeans include first contact element means fastened to the outer end ofsaid axle and second contact element means fastened to said one side ofsaid housing of said sensing means, said first and second contactelement means being in slidable contact with one another.

11. The improvement defined in claim 10, wherein said first and secondcontact element means are in slidable contact at a single point, saidpoint being arranged on said common axis.

12. The improvement defined in claim 8, wherein said wheel is connectedto a rotatable axle, and wherein said electrical contact means isarranged to rotate with said axle.

13. The improvement defined in claim 3, wherein said wheel includes adetachable wheel rim having a central opening, and wherein said housingof said sensing means has a maximum width which is less than thediameter of said central opening.

14. The improvement defined in claim 1, wherein said wheel is arrangedto rotate on an axle having a cavity in the outer end thereof, andwherein at least a portion of said electrical contact means is arrangedin said cavity.

15. The improvement defined in claim I, wherein said wheel is arrangedto rotate on an axle having a bore extending longitudinally therein, andwherein said electrical line passes through said bore.

least one brakeshoe, and wherein said at least one brakeshoe contains ametal insert connected to said chassis of said vehicle for reducing theground resistance between said wheel and said chassis.

18. The improvement defined in claim 17, wherein said metal insert isarranged to wear down together with said at least one brakeshoe.

19. The improvement defined in claim 6, wherein said signal transmittingmeans includes two electromagnetically coupled annular coils arranged ona common axis with said wheel.

20. The improvement defined in claim 3, wherein said sensing means isarranged on said member, eccentrically with respect to the axis of saidwheel, and wherein said member is an annular disc having counterweightmeans, arranged diametrically opposite to said sensing means, forbalancing said sensing means.

21. The improvement defined in claim 20, wherein said wheel includes awheel hub, a wheel rim and a plurality of bolts for attaching said rimto' said hub, and wherein said member is attached to said wheel rim andsaid wheel hub with at least some of said plurality of bolts.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,563,351 Dated February 16th, 1971 ln n ofls) Heinz Leiber and HeinzWehde It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

In the heading of the patent, line 2 change "Im Enklert" to Leimen-.Column 1 line 15, after "least" delete "on". Column 2 line 48 after' -spfi insert a hyphen Column 4 line 16, after "or" delete "die".

Signed and sealed this 6th day of July 1 971 (SEAL) Attest:

EDWARD M.FLETGHER,JR. Attesting Officer WILLIAM E. SGHUYLER, JCommissioner of Patent

1. An antiskid brake control system for wheeled vehicles comprisingelectrically actuatable means for controlling the brake pressure appliedto a wheel; means for sensing changes in the absolute rotational speedof such wheel, said sensing means comprising a hermetically sealedhousing, an inertial mass arranged within said housing and rotatablerelative to said housing within a limited angular range, electricalsignaling means responsive to the relative rotation between said massand said housing and at least one insulated electrical conductorconnected to said signaling means and passing through said housing; anelectrical line connecting said sensing means with said brake pressurecontrol means; connecting means, associated with said housing and suchwheel, for detachably connecting said housing to such wheel; andelectrical contact means, arranged on one siDe of said housing, fordetachably connecting said electrical line with said electricalconductor.
 2. The improvement defined in claim 1, wherein saidconnecting means is arranged to directly connect said housing to saidwheel.
 3. The improvement defined in claim 1, wherein said connectingmeans includes a member which is rigidly connected to said wheel andsaid connecting means is arranged to directly connect said housing tosaid member.
 4. The improvement defined in claim 1, wherein said contactmeans are arranged on the side of said housing which faces said wheel.5. The improvement defined in claim 1, wherein said contact means areconstructed to provide an automatic connection between said electricalline and said electrical conductor when said sensing means is attachedto said wheel and to automatically disconnect said electrical line fromsaid electrical conductor when said sensing means is removed from saidwheel.
 6. The improvement defined in claim 1, further comprising meansfor transmitting a signal, during the rotation of said wheel, from saidelectrical signaling means in said sensing means to said means forcontrolling the brake pressure, said signal transmitting means beingseparately arranged from said sensing means.
 7. The improvement definedin claim 6, wherein said wheel is mounted on at least one wheel bearingand said signal transmitting means is arranged in the proximity of saidat least one wheel bearing.
 8. The improvement defined in claim 1,wherein said sensing means is arranged on a common axis with said wheel.9. The improvement defined in claim 1, wherein said sensing means isarranged eccentrically with respect to the axis of said wheel. 10, Theimprovement defined in claim 8, wherein said wheel is arranged to rotateabout a nonrotatable axle, and wherein said electrical contact meansinclude first contact element means fastened to the outer end of saidaxle and second contact element means fastened to said one side of saidhousing of said sensing means, said first and second contact elementmeans being in slidable contact with one another.
 11. The improvementdefined in claim 10, wherein said first and second contact element meansare in slidable contact at a single point, said point being arranged onsaid common axis.
 12. The improvement defined in claim 8, wherein saidwheel is connected to a rotatable axle, and wherein said electricalcontact means is arranged to rotate with said axle.
 13. The improvementdefined in claim 8, wherein said wheel includes a detachable wheel rimhaving a central opening, and wherein said housing of said sensing meanshas a maximum width which is less than the diameter of said centralopening.
 14. The improvement defined in claim 1, wherein said wheel isarranged to rotate on an axle having a cavity in the outer end thereof,and wherein at least a portion of said electrical contact means isarranged in said cavity.
 15. The improvement defined in claim 1, whereinsaid wheel is arranged to rotate on an axle having a bore extendinglongitudinally therein, and wherein said electrical line passes throughsaid bore.
 16. The improvement defined in claim 1, wherein said sensingmeans is electrically connected to said brake control means through theground connection between said wheel and the chassis of said wheeledvehicle.
 17. The improvement defined in claim 16, wherein the brakepressure applied to said wheel is applied by means of at least onebrakeshoe, and wherein said at least one brakeshoe contains a metalinsert connected to said chassis of said vehicle for reducing the groundresistance between said wheel and said chassis.
 18. The improvementdefined in claim 17, wherein said metal insert is arranged to wear downtogether with said at least one brakeshoe.
 19. The improvement definedin claim 6, wherein said signal transmitting means includes twoelectromagnetically coupled annular coils arranged on a common axis withsaid wheel.
 20. The improvemenT defined in claim 3, wherein said sensingmeans is arranged on said member, eccentrically with respect to the axisof said wheel, and wherein said member is an annular disc havingcounterweight means, arranged diametrically opposite to said sensingmeans, for balancing said sensing means.
 21. The improvement defined inclaim 20, wherein said wheel includes a wheel hub, a wheel rim and aplurality of bolts for attaching said rim to said hub, and wherein saidmember is attached to said wheel rim and said wheel hub with at leastsome of said plurality of bolts.